Data compression

I am the author of gzip, a data compression program
relatively popular on the Internet, designed to replace compress.
Mark Adler
wrote the decompression code. For this work Mark and I received the
Usenix 2009 STUG award
(video).

See the gzip home page
for gzip sources, executables and frequently asked questions.
If you have a question about gzip, look first for an answer
there. If you don't find the answer,
write to
support@gzip.org.

I have written the compression code of the portable archiver
zip of the
Info-Zip group.
zip and unzip are compatible with the
pkzip archiver for MSDOS. Sources and executables for many
systems are
here.

In collaboration with
Mark Adler, I have written the
zlib,
data compression library, which lets you compress or decompress
data in memory or read and write files in the
gzip format.

The data format used by the zlib library is described by RFCs (Request for
Comments)
1950 (zlib format) and
1951 (deflate format).
This format is used in particular in the
PNG image format.
A closely related format has been adopted for one of the
PPP
compression protocols. zlib is used in many other applications
(Netscape, Apache, PGP, Java, Microsoft Office...).

The zlib authors can be reached by e-mail at
zlib@gzip.org .
Please read the FAQ and
the manual before asking
us for help. We are getting too many questions which already have an
answer in the zlib documentation.

The sources of my fractal compression program are here
(tar.gz or zip
format). If you want to understand how the program works, or if you
need help about the program, please buy the book first.

Finally, I created the
FAQ (Frequently Asked Questions) of the
comp.compression newsgroup. (Also
available by
ftp.)
In particular if you wonder how to extract a file in format X on a
system Y, please check the FAQ before posting or mailing.

Security

I have a strong interest in computer security. See my specific
security page
about this.

Patents

Before the release of gzip, I studied a
lot of patents on data compression to make sure that my implementation
avoided all of them. See
section 8 of the comp.compression
FAQ for a small subset (several dozen) of all patents I've looked at.

During my search, I found two interesting patents on a process which
is mathematically impossible: compression of random data. This is
somewhat equivalent to patents on perpetual motion machines. Check
here for a short analysis of these two
patents.

Work

In 1978, I published together with James Lequeux,
my professor at the
Ecole Polytechnique,
an article on the galactic distribution of
pulsars (Astronomy and
Astrophysics, 70, L15-L18, 1978). A pulsar is not visually appealing,
so have a look instead at Cygnus Loop
which contains a pulsar. The
Crab Nebula results from the explosion of a supernova in 1054; it
houses a pulsar in its center.

In 1979 and 1980, I studied the stratospheric turbulence within the
Service d'Aéronomie du CNRS,
by attaching a very sensitive anemometer under a stratospheric balloon
filled with hydrogen.

From 1981 to 1989 I participated in the construction of code generators
and real-time systems for the
Ada language within Alsys
(renamed first Thomson Software Products then Aonix).
I was a member of the Ada language design team.

From 1990 to 1995 I was responsible for the real-time executive of
the Chorus micro-kernel.